Use and application of damp-proof renders/plasters

The Weber damp-proof renders/plasters (all in accordance with the guidelines of WTA (Scientific and Technical Working Group for Building Conservation and Monument Preservation, Germany) are used indoors and outdoors in one or two layers up to 40 mm totally, depending upon roughness and salt content of masonry. Thanks to their large pore structure they are able to take over crystal-building salts and to store them within their porous body. The removal of damaged renders in a distance of 80 cm above the visibly damaged area with moisture and salt attack is a prerequisite for the substrate preparation. When used on internal waterproofing layers, damp-proof plasters regulate the condensation dampness within the rooms by up taking the condensation moisture for a certain period of time.

Step by step


    1. The evaluation of moisture and salt content of masonries as well as knowledge of building uses are prerequisite for a professional application.


    2. Moist or damp renders/plasters must be removed by mechanical means.


    3. Scrape out the damaged and salt-loaded joint mortar network in a depth of at least 2 cm.


    4. Prepared old masonry wall.


    5. The quick-setting stipple coat weber.san 951 S provi-des a bonding with the substrate. It is applied net-like (i.e. with a surface coverage of 50%), using the throw-on technique with a triangular hawk trowel. If an internal waterproofing will be applied afterwards, the coverage must be 100%.


    6. Application of the damp-proof render/plaster weber.san 954, using a flat trowel.


    7. For application of the damp-proof render/plaster by machine (for ex. mono fu of the company M-tec) we recommend a screw jacket  D 6-3 and a supplementary mixer.


    8. In case of 2-layer application comb the first layer horizontally immediately with the flat trowel weber.sys Aufstreichkelle, equipped with the 5-mm triangular notch blade Zahnleiste no. 2 or a tiler trowel (notch 6 - 8 mm) before applying the second layer.


    9. Rule the damp-proof render/plaster with an aluminium beam.


    10. Smooth weber.san 954 with a sponge board.


    11. Whenever damp-proof renders/plasters are applied on water-proofing coatings, one layer is in general sufficient. Insert the woven glass fiber mesh weber.sys 987 in the upper third of the render layer. The render takes over the task of moisture regulation, i.e. temporary uptake of condensate moisture.


    12. Measures in accordance with the salt content of masonry substrate.